Toxocariasis as an Elderly Zoonosis: Seroprevalence, Neurocognitive Assessment, and Associated Risk Factors in Persons 50 Years and Older

Toxocariasis, a geohelminthiasis caused by <i>Toxocara canis</i> and <i>Toxocara cati</i> nematodes, has an estimated 19% seroprevalence worldwide. Although children have been considered more prone to infection, adults and the elderly may also be considered at risk. Accordingly, the present study aimed to assess the associated risk factors for <i>Toxocara</i> spp. seropositivity in a population of 290 individuals over 50 years old, attended by the Public Health System in western São Paulo state. Socioepidemiological information was obtained by a semi-structured questionnaire, a blood (serum) sample, and a neurocognitive function assessment by the 10-point cognitive screener (10-CS). Overall, 89/290 (30.7%; 95% CI: 25.7-36.2%) individuals presented anti-<i>Toxocara</i> spp. IgG antibodies by ELISA. Multivariate analysis revealed that individuals raising both dogs and cats were 3-fold more likely to be seropositive than the ones without any pet (<i>p</i> = 0.002), while educational level resulted in an associated protective factor (<i>p</i> = 0.001). No seropositivity influence was observed for the other evaluated variables, including age, gender, monthly income, consumption of drinkable water or raw/undercooked meat, having a dirty floor at home, contact with soil, washing vegetables and hands before meals, and onychophagy. Although seropositivity was not statistically associated with dementia (<i>p</i> = 0.198) and neuropsychiatric disorder (<i>p</i> = 0.440), results herein indicated toxocariasis as a likely under-reported and neglected infection in the older human population. As an immunosenescence risk group that should be continuously monitored, elderly pet owners may be at risk and should be extra careful with self-hygiene and pet deworming, particularly when owning multiple pet species, to reduce the risk of toxocariasis infection.